#include <iostream>
using namespace std;

void heapify(int arr[], int n, int i)
{
    int largest = i;  // Initialize largest as root
    int l = 2*i + 1;  // left = 2*i + 1
    int r = 2*i + 2;  // right = 2*i + 2
 
    if (l < n && arr[l] > arr[largest])
        largest = l;
 

    if (r < n && arr[r] > arr[largest])
        largest = r;
 
    if (largest != i)
    {
        swap(arr[i], arr[largest]);
        heapify(arr, n, largest);
    }
}
 

void heapSort(int arr[], int n)
{

    for (int i = n / 2 - 1; i >= 0; i--)
        heapify(arr, n, i);
 

    for (int i=n-1; i>=0; i--)
    {
        swap(arr[0], arr[i]);
 
        heapify(arr, i, 0);
    }
}
 
int main()
{
    int arr[] = {12, 11, 13, 5, 6, 7};
    int n = sizeof(arr)/sizeof(arr[0]);
 
    heapSort(arr, n);
 
    cout << "Sorted array is \n";
    for (int i=0; i<n; ++i)
        cout << arr[i] << " ";
}
